Getter devices are well known in the art and are used for a variety of reasons.
One use is to maintain the vacuum in electrical discharge vessels thus increasing the effective working life. Getter devices can also be used within gas or vapour filled electrical discharge vessels where their main function is to reduce reactive gases.
Getter materials are usually divided into two main groups.
Getter materials of the first group are called "flash" or "evaporable" getter materials. These getter materials derive their name from the fact that getter material is evaporated from a container by quick heating or flashing. The getter material is then dispersed onto a suitable surface. It is frequently found that, within the electronic device, there is no suitable surface on which to deposit the evaporable getter material. For this and other reasons it is therefore necessary to use "non-evaporable" getter devices. Many non-evaporable getter devices and materials are known. For examples see U.S. Pat. No. 4,312,669; 4,269,624; 4,146,497; 4,137,012; 4,119,488; 3,961,897; 3,926,832; 3,620,645; 3,203,901; and 3,584,253.
In some cases, the physical dimensions of a getter device itself constitute a problem for the location of the getter device within the electron tube. To some extent this has been solved by placing the getter device within the pumping tubulation provided to evacuate the device. Examples of such a location are provided in U.S. Pat. No. 3,784,862 in the case of an evaporable getter and in Italian Patent No. 1,011,230 for the case of a non-evaporable getter.
Whether the getter be evaporable or non-evaporable it is necessary to provide the getter device with a support element to position it within the tubulation. With the getter device of Italian Patent No. 1,011,230, in order to provide activation of the getter device by high frequency induction heating it is necessary to provide a section of the tubulation in ceramic material which adds considerably to the expense of the tube. It is also known that when space is at a premium, a getter device with an internal spiral heater such as the one described in U.S. Pat. No. 3,584,253 can be used. However, this requires the use of special chambers provided with electrical feedthroughs which again is very expensive. Furthermore, when the getter is provided with a support element or is provided with a self-contained heater, when it is subjected to shock or vibration, the getter device may detach from its required position or provoke the production of loose particles.
It is therefore an object of the present invention to provide a getter device for a pumping tubulation which is free from one or more defects of prior getter devices.
It is one object of the present invention to provide a getter device free from a separate support element.
It is another object of the present invention to provide a getter device in a pumping tubulation which can be heated by HF induction currents without the necessity of providing a ceramic portion to the tubulation.
It is a further object of the present invention to provide a getter device which does not require the use of special chambers.
It is yet another object of the present invention to provide a getter device for a pumping tubulation which is free from the production of loose particles in the presence of shocks or vibrations.